1. Technical Field of the Invention
The present invention relates generally to automotive alternators and rectifiers. More particularly, the invention relates to an automotive alternator which includes a rectifier having high-strength heat sinks.
2. Description of the Related Art
In recent years, engine rooms in vehicles have been reduced to meet the requirements of adopting a slant-nose design to reduce the running resistance and securing more sufficient space in the vehicle compartments. Meanwhile, the number of engine accessories to be installed in an engine room has increased. Consequently, automotive alternators are now subjected to higher ambient temperatures in engine rooms and required to be more compact.
On the other hand, due to an increase in electric load for improving comfort and the security of the vehicle, automotive alternators are now required to have a larger power capacity and thus come to generate a greater amount of heat.
In particular, among the components of an automotive alternator, a rectifier that includes a plurality of rectifying elements (e.g., diodes) generally experiences a great rise in temperature during operation of the automotive alternator. Accordingly, it is required to secure sufficient cooling of the rectifier without increasing the size and cost of the automotive alternator.
U.S. Pat. No. 6,809,443 discloses a rectifying device incorporated in an automotive alternator. Specifically, in the rectifying device, rectifying elements are press-fitted in receiving holes formed in a pair of cooling fins (i.e., heat sinks), thereby eliminating conventional soldering operation; the cooling fins each have a plurality of ribs extending radially with respect to a rotary shaft of the automotive alternator, thereby improving the cooling performance of the cooling fins without increasing the size of the automotive alternator.
US Patent Application Publication No. 2004/0256924 discloses a rectifier incorporated in an automotive alternator. Specifically, in the rectifier, rectifying elements are press-fitted in press-in holes formed in a pair of radiating fins (i.e., heat sinks); the radiating fins each have a plurality of radial sub-fins that extends radially with respect to a rotary shaft of the automotive alternator; the radiating fins each further have a plurality of arc-like sub-fins, each of which is formed in the vicinity of one of the press-in holes, thereby enhancing the strength thereof; the radiating fins each have a large thickness in the vicinities of the press-in holes, so as to prevent cracks from occurring during the operation of press-fitting the rectifying elements into the press-in holes.
However, in the above prior art rectifying device and rectifier, since the cooling or radiating fins have formed therein the receiving or press-in holes and the ribs or sub-fins, they have a very complicated shape. Thus, thickness-reducing portions and stress-concentrating portions may exist in the cooling or radiating fins; those portions may disenable the cooling or radiating fins from withstanding stress caused by the operation of press-fitting the rectifying elements into the receiving or press-in holes and thus may cause the cooling or radiating fins to crack.
Moreover, to minimize the manufacturing cost of the cooling or radiating fins, it is desirable to manufacture those by aluminum die casting. However, in some cases, it may be difficult to manufacture the cooling or radiating fins by aluminum die casting without defects; consequently, it may become further difficult to prevent the manufactured cooling or radiating fins from cracking during the press-fit operation.